Consider the signal flow graph shown in the figure below. The gain $\frac{x_{5}}{x_{1}}$ is
- $\frac{1-\left(b e+c f+d g\right)}{a b c}$
- $\frac{b e d g}{1-(b e+c f+d g)}$
- $\frac{a b c d}{1-\left(b e+c f+d g\right)+bedg}$
- $\frac{1-\left(b e+cf+d g\right)+b ed g}{a b c d}$